OK, let's crack this. We're given 138 and our task is to multiply it by 84. Essentially, we'll be adding 138 to itself 84 times.
Step 1: 0 + 138 = 138
Step 2: 138 + 138 = 276
Step 3: 276 + 138 = 414
Step 4: 414 + 138 = 552
Step 5: 552 + 138 = 690
Step 6: 690 + 138 = 828
Step 7: 828 + 138 = 966
Step 8: 966 + 138 = 1104
Step 9: 1104 + 138 = 1242
Step 10: 1242 + 138 = 1380
Step 11: 1380 + 138 = 1518
Step 12: 1518 + 138 = 1656
Step 13: 1656 + 138 = 1794
Step 14: 1794 + 138 = 1932
Step 15: 1932 + 138 = 2070
Step 16: 2070 + 138 = 2208
Step 17: 2208 + 138 = 2346
Step 18: 2346 + 138 = 2484
Step 19: 2484 + 138 = 2622
Step 20: 2622 + 138 = 2760
Step 21: 2760 + 138 = 2898
Step 22: 2898 + 138 = 3036
Step 23: 3036 + 138 = 3174
Step 24: 3174 + 138 = 3312
Step 25: 3312 + 138 = 3450
Step 26: 3450 + 138 = 3588
Step 27: 3588 + 138 = 3726
Step 28: 3726 + 138 = 3864
Step 29: 3864 + 138 = 4002
Step 30: 4002 + 138 = 4140
Step 31: 4140 + 138 = 4278
Step 32: 4278 + 138 = 4416
Step 33: 4416 + 138 = 4554
Step 34: 4554 + 138 = 4692
Step 35: 4692 + 138 = 4830
Step 36: 4830 + 138 = 4968
Step 37: 4968 + 138 = 5106
Step 38: 5106 + 138 = 5244
Step 39: 5244 + 138 = 5382
Step 40: 5382 + 138 = 5520
Step 41: 5520 + 138 = 5658
Step 42: 5658 + 138 = 5796
Step 43: 5796 + 138 = 5934
Step 44: 5934 + 138 = 6072
Step 45: 6072 + 138 = 6210
Step 46: 6210 + 138 = 6348
Step 47: 6348 + 138 = 6486
Step 48: 6486 + 138 = 6624
Step 49: 6624 + 138 = 6762
Step 50: 6762 + 138 = 6900
Step 51: 6900 + 138 = 7038
Step 52: 7038 + 138 = 7176
Step 53: 7176 + 138 = 7314
Step 54: 7314 + 138 = 7452
Step 55: 7452 + 138 = 7590
Step 56: 7590 + 138 = 7728
Step 57: 7728 + 138 = 7866
Step 58: 7866 + 138 = 8004
Step 59: 8004 + 138 = 8142
Step 60: 8142 + 138 = 8280
Step 61: 8280 + 138 = 8418
Step 62: 8418 + 138 = 8556
Step 63: 8556 + 138 = 8694
Step 64: 8694 + 138 = 8832
Step 65: 8832 + 138 = 8970
Step 66: 8970 + 138 = 9108
Step 67: 9108 + 138 = 9246
Step 68: 9246 + 138 = 9384
Step 69: 9384 + 138 = 9522
Step 70: 9522 + 138 = 9660
Step 71: 9660 + 138 = 9798
Step 72: 9798 + 138 = 9936
Step 73: 9936 + 138 = 10074
Step 74: 10074 + 138 = 10212
Step 75: 10212 + 138 = 10350
Step 76: 10350 + 138 = 10488
Step 77: 10488 + 138 = 10626
Step 78: 10626 + 138 = 10764
Step 79: 10764 + 138 = 10902
Step 80: 10902 + 138 = 11040
Step 81: 11040 + 138 = 11178
Step 82: 11178 + 138 = 11316
Step 83: 11316 + 138 = 11454
Step 84: 11454 + 138 = 11592

So, 138*84 = 11592